Protective Effect of Pharmacologic Preconditioning with Pioglitazone on Random-Pattern Skin Flap in Rat is Mediated by Nitric Oxide System Sajjad Afraz, M.D., Ali Kamran, M.D., Kasra Moazzami, M.D., Behtash G. Nezami, M.D., and Ahmad Reza Dehpour, Ph.D. 1 Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Originally submitted August 1, 2011; accepted for publication October 13, 2011 Background. Pioglitazone, a thiazolidinedione, is primarily used as an antidiabetic agent. In addition, recent reports have identified anti-ischemic and anti- inflammatory properties of pioglitazone through nitric oxide (NO) pathways. Objective. To determine the protective effects of pio- glitazone on random-pattern skin flaps in a rat model. Methods. Forty-eight male Rats were randomly assigned to eight groups. Bipedicled dorsal skin flaps (2 3 8 cm) were elevated at the midline. In pharmaco- logic preconditioning groups, three different doses of pioglitazone (25, 40, 80, mg/kg; doses were selected ac- cording to our pilot study) gavaged 4 h before elevating flaps. Seven days after operation, the survival of skin flap was measured. For investigating the role of NO system, in other groups the nitric oxide synthase inhib- itor N-nitro-L-arginine methyl ester hydrochloride (L-NAME, 10 mg/kg) was administered alone or with an effective dose of pioglitazone. Finally, in another group, subeffective dose of nitric oxide precursor L-ar- ginine (100 mg/kg) was coadministered with subeffec- tive pioglitazone. Results. Significant increase in flap survival was seen with pioglitazone (40 mg/kg). This protective effect was abolished by systemic administration of L-NAME (10 mg/kg). Coadministration of subeffective doses of pioglitazone with subeffetcive L-arginine sig- nificantly improved flap survival. Conclusion. Pharmacologic preconditioning with pioglitazone improves survival of random-pattern skin flaps in rats through NO dependent mecha- nisms. Ó 2012 Elsevier Inc. All rights reserved. Key Words: skin flap; ischemic injury/prevention; pio- glitazone; nitric oxide. INTRODUCTION Skin flaps have been increasingly used in reconstruc- tive surgery for the closure of surgical defects. Because of technical simplicity, random-pattern flaps are widely used in this regard. However, despite major advan- tages, ischemic tissue necrosis remains a troublesome complication of random-pattern skin flap surgery due to the inadequate vascular perfusion of the flap [1, 2]. The resultant tissue loss would therefore produce sig- nificant cosmetic and functional deficits. Thus, many attempts have been made to increase the flap survival by applying preoperative prophylactic treatments in order to improve flap viability. A variety of drugs, in- cluding morphine [3], adenosine [4], monophosphoryl lipid A [5], and dexamethasone [6], have been used in this regard [7]. However, undesirable side effects, high drug prices, or restricted availability have made some of these drugs impractical for clinical use [8]. Thiazolidinediones such as pioglitazone are synthetic agonists of the nuclear receptor and transcription factor peroxisome proliferator-activated receptors (PPARs),which are categorized as oral antidiabetic drugs [9]. These agents act to enhance insulin sensitiv- ity and reduce serum glucose in diabetic patients [9, 10]. Also, regarding adverse reactions, in this group pio- glitazone has been used without evidence of significant toxicity [11]. In addition to glucose lowering effects, these agents have been shown to protect against ische- mic damage through their inhibition of expression of a broad range of inflammatory mediators [12]. Also, their protective effects against ischemic reperfusion 1 To whom correspondence and reprint requests should be addressed at Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, P.O. Box 13145-784, Tehran, Iran. E-mail: dehpour@yahoo.com. 0022-4804/$36.00 Ó 2012 Elsevier Inc. All rights reserved. 696 Journal of Surgical Research 176, 696–700 (2012) doi:10.1016/j.jss.2011.10.013